Humidity: Humidity has been closely related to daily life for a long time, but it is difficult to express it in terms of quantity. The physical quantity commonly used in daily life to represent humidity is the relative humidity of the air. Expressed as% RH. There is a close relationship between relative humidity and temperature in the derivation of physical quantities. A certain volume of sealed gas has a higher temperature and lower relative humidity, and a lower temperature leads to a higher relative humidity. It involves complex knowledge of thermal engineering.

Some definitions of humidity: Relative humidity: In metrology, humidity is defined as the "quantity of the state of an object". The humidity referred to in daily life is relative humidity, expressed in RH%. In short, it refers to the percentage of water vapor content (vapor pressure) in a gas (usually air) that is equal to its saturated vapor content (vapor pressure) in air.

Humidity: refers to the actual amount of water vapor contained in a unit volume of air, usually measured in grams. Temperature has a direct impact on humidity. Generally, the higher the temperature, the more water vapor is emitted, and the higher the humidity; On the contrary, the humidity is low.

Saturation humidity: The maximum amount of water vapor that can be contained in air per unit volume at a certain temperature. If this limit is exceeded, excess water vapor will condense and turn into water droplets, and the air humidity at this point becomes known as saturation humidity. The saturation humidity of air is not fixed and varies with temperature. The higher the temperature, the more water vapor can be contained per unit volume of air, and the higher the saturation humidity.

Dew point: refers to air containing a certain amount of water vapor (humidity). When the temperature drops to a certain level, the water vapor will reach saturation (saturation humidity) and begin to liquefy into water. This phenomenon is called condensation. The temperature at which water vapor begins to liquefy into water is called the "dew point temperature," abbreviated as "dew point. If the temperature continues to drop below the dew point, supersaturated water vapor in the air will condense into water droplets on the surface of the object. In addition, wind is closely related to the temperature and humidity in the air, and is also one of the important factors affecting changes in air temperature and humidity.